Defending champion Ronnie O'Sullivan suffered a shock 9-5 defeat by Joe Perry to crash out of the UK Championship in round two on Tuesday.
John Higgins, Stephen Maguire and Shaun Murphy all won, but the title holder collapsed dramatically.
O'Sullivan scorched into a 5-3 lead overnight with three centuries, but his game fell apart in the second session.
Perry played superbly, but a series of errors from the world number one gifted frame after frame to his opponent.
Having seen Perry win the first three frames of the afternoon to trail 5-6, O'Sullivan conceded the 12th frame, the last before the mid-session interval, by deliberately flicking the white away with his cue when just 23-0 down.
"It might have looked like I lost my head or whatever, but I'm sure I'll bounce back"
"It is just a little £250 fine, a letter in the post," he told BBC Sport. "I have had a few of them before, and I will have a few more I suppose.
"I was quite happy I did it really. I just wanted to get out of there, have a cup of tea and come back again. But it still didn't make a difference really. It is no big deal."
O'Sullivan preferred to give credit to Perry, a World Championship semi-finalist earlier this year, who claimed the best win of his career.
"I just got outplayed on the day," O'Sullivan told BBC Sport.
"It might have looked like I lost my head or whatever, but I'm sure I'll bounce back somewhere along the line.
"He played great - I wasn't going to win today. His safety was great, he scored when he got in and didn't miss much. Sometimes you've just got to hold your hands up."
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"It's been a good competition for me," said Perry, who reached the quarter-finals for the fifth time.
"I do enjoy the longer matches. I was 5-3 down overnight and that didn't seem that bad as Ronnie gave me a bit of snooker lesson on Monday.
"I knew I was still in it at 5-3 and that's how it turned out to be."
Mark Williams also progressed to the quarter-finals after coming back from 6-3 down to beat Graeme Dott 9-7 in a nervous encounter between former world champions.
The Welshman will play World Championship finalist Ali Carter, who beat fellow Englishman Peter Ebdon 9-5, in the last eight.
Higgins eased past Ding Junhui 9-4 despite the Chinese player making a 147 break in the third frame of the match.
The Scot will play compatriot Stephen Maguire in the quarter-finals.
Maguire beat Neil Robertson 9-8 with a magnificent break of 104 in a dramatic closing match of the evning, after the Australian had missed a black to win it in the previous frame.
Murphy, meanwhile, continued his revival by seeing off Northern Irishman Mark Allen 9-7. He will play Stephen Lee in the last eight.
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